Logical Reasoning

PT143 · S4 · Q11 A development company has proposed

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A development company has proposed building an airport near the city of Dalton.

Conclusion

It's unlikely that the airport will be built.

Evidence

If a majority of residents favor the proposed airport, it'll be built + It's unlikely that a majority will favor the proposal, since most of them think the airport would create noise problems.

Evaluation

If we're doing Flaw and we see conditional logic, we should be on guard for the Necessary vs. Sufficient flaw, where an author presents a conditional rule but then applies it in a backwards or opposite fashion.

This argument tried to illegally argue the opposite of the conditional. We know: majority favors → airport will be built A → B and this is arguing majority favors → airport will be built ~A → ~B

Goal

Look for an answer describing the Necessary vs. Sufficient flaw. Or look for a conversational objection, that even if a majority doesn't favor the airport, there might be some other possibility that would also trigger the airport being built (a rich donor, for example).

11.

The reasoning in the argument is flawed in that the argument

  1. Correct

    treats a sufficient condition for

    Why this is right

    A majority of residents' favoring the airport is identified as a guarantee that the airport will be built (a sufficient condition). When the author goes on to act like, "If a majority doesn't approve, then it won't be built", she is acting like their approval is necessary. Any time we see this answer, we check whether there was any conditional logic in the argument and then see if the author reasoned through that rule in an illegal backwards or opposite fashion.

    Skill tested: Flaw · how this choice captures the argument's function is the move to repeat next time.

    70% picked this

  2. concludes that something must be

    Bad Conclusion / Premise Match

    Does the conclusion say that something must be true? Nope. It says something is "unlikely" to be true. We can eliminate without reading the rest. However, the rest is also wrong. Nothing in the premises said, "Most people believe that the airport will probably not be built". It said, "Most people don't favor the the idea of the airport being built".

    7% picked this

  3. concludes, on the basis that

    Bad Conclusion Match

    Does the author conclude that an event will not occur? Nope. She concludes that an event is unlikely to occur.

    14% picked this

  4. fails to consider whether people

    Weak Impact

    This starts to hint at the idea that there's more than one way to get that airport built. Maybe the local residents don't favor the proposal, so THAT rule won't get triggered, but there still might be other ways the airport gets built. However, in order for this answer to do much, we'd have to add on our own idea that, "If people nearby favor the airport, the airport will be built". Without that rule, this answer doesn't pose much of an objection.

    5% picked this

  5. overlooks the possibility that a

    Weak Impact

    Just like (D), this hints at some other possible reason or consideration that might be a different way to trigger building the airport, but we don't know that the faint possibility that the airport could benefit the economy would change anything.

    4% picked this

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